[PATCH v2 0/2] iio: adc: mcp3422: apply bit manipulation macros

[PATCH v2 0/2] iio: adc: mcp3422: apply bit manipulation macros

[Marcelo Machado Lage]

This patch set rewrites several open-coded bit manipulation parts of
the MCP3421/2/3/4/5/6/7/8 driver code using bit.h and bitfield.h
macros.

This follows a request by Andy Shevchenko. Thanks, Andy!

Marcelo Machado Lage (2):
  iio: adc: mcp3422: rewrite mask macros using bitfield macros
  iio: adc: mcp3422: write bit operations with bitfield macros

 drivers/iio/adc/mcp3422.c | 60 ++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 35 deletions(-)

-- 
2.34.1

[PATCH v2 1/2] iio: adc: mcp3422: rewrite mask macros using bitfield macros

[Marcelo Machado Lage]

Rewrite MCP3422_CHANNEL_MASK, MCP3422_PGA_MASK, MCP3422_PGA_MASK
and MCP3422_CONT_SAMPLING using GENMASK() and BIT() macros from
bitfield.h.

The other macros MCP3422_SRATE_{240, 60, 15, 3} were not changed
because they are also used as array indices.

Signed-off-by: Marcelo Machado Lage <marcelomlage@usp.br>
Co-developed-by: Vinicius Lira <vinilira@usp.br>
Signed-off-by: Vinicius Lira <vinilira@usp.br>
---
 drivers/iio/adc/mcp3422.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
index 50834fdcf738..59bf73304588 100644
--- a/drivers/iio/adc/mcp3422.c
+++ b/drivers/iio/adc/mcp3422.c
@@ -13,6 +13,7 @@
  * voltage unit is nV.
  */
 
+#include <linux/bits.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
@@ -25,9 +26,9 @@
 #include <linux/iio/sysfs.h>
 
 /* Masks */
-#define MCP3422_CHANNEL_MASK	0x60
-#define MCP3422_PGA_MASK	0x03
-#define MCP3422_SRATE_MASK	0x0C
+#define MCP3422_CHANNEL_MASK	GENMASK(6, 5)
+#define MCP3422_PGA_MASK	GENMASK(1, 0)
+#define MCP3422_SRATE_MASK	GENMASK(3, 2)
 #define MCP3422_SRATE_240	0x0
 #define MCP3422_SRATE_60	0x1
 #define MCP3422_SRATE_15	0x2
@@ -36,7 +37,7 @@
 #define MCP3422_PGA_2	1
 #define MCP3422_PGA_4	2
 #define MCP3422_PGA_8	3
-#define MCP3422_CONT_SAMPLING	0x10
+#define MCP3422_CONT_SAMPLING	BIT(4)
 
 #define MCP3422_CHANNEL(config)	(((config) & MCP3422_CHANNEL_MASK) >> 5)
 #define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
-- 
2.34.1

[PATCH v2 2/2] iio: adc: mcp3422: write bit operations with bitfield macros

[Marcelo Machado Lage]

Replace manual bit manipulations with FIELD_GET(), FIELD_PREP() and
FIELD_MODIFY() calls. The resulting code is more readable and
maintainable, and 6 macros previously defined in the header are not
needed anymore.

Following a request by Jonathan Cameron, this version of the patch
has 3 less macros than v1, now replaced by inline calls of FIELD_GET().
Thanks, Jonathan! 

Signed-off-by: Marcelo Machado Lage <marcelomlage@usp.br>
Co-developed-by: Vinicius Lira <vinilira@usp.br>
Signed-off-by: Vinicius Lira <vinilira@usp.br>
---
 drivers/iio/adc/mcp3422.c | 51 +++++++++++++++------------------------
 1 file changed, 20 insertions(+), 31 deletions(-)

diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
index 59bf73304588..a2a7a850a825 100644
--- a/drivers/iio/adc/mcp3422.c
+++ b/drivers/iio/adc/mcp3422.c
@@ -13,6 +13,7 @@
  * voltage unit is nV.
  */
 
+#include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
@@ -39,14 +40,6 @@
 #define MCP3422_PGA_8	3
 #define MCP3422_CONT_SAMPLING	BIT(4)
 
-#define MCP3422_CHANNEL(config)	(((config) & MCP3422_CHANNEL_MASK) >> 5)
-#define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
-#define MCP3422_SAMPLE_RATE(config)	(((config) & MCP3422_SRATE_MASK) >> 2)
-
-#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
-#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
-#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
-
 #define MCP3422_CHAN(_index) \
 	{ \
 		.type = IIO_VOLTAGE, \
@@ -109,7 +102,7 @@ static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
 static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
 {
 	int ret = 0;
-	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
+	u8 sample_rate = FIELD_GET(MCP3422_SRATE_MASK, adc->config);
 	u8 buf[4] = {0, 0, 0, 0};
 	u32 temp;
 
@@ -137,18 +130,18 @@ static int mcp3422_read_channel(struct mcp3422 *adc,
 
 	mutex_lock(&adc->lock);
 
-	if (req_channel != MCP3422_CHANNEL(adc->config)) {
+	if (req_channel != FIELD_GET(MCP3422_CHANNEL_MASK, adc->config)) {
 		config = adc->config;
-		config &= ~MCP3422_CHANNEL_MASK;
-		config |= MCP3422_CHANNEL_VALUE(req_channel);
-		config &= ~MCP3422_PGA_MASK;
-		config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
+
+		FIELD_MODIFY(MCP3422_CHANNEL_MASK, &config, req_channel);
+		FIELD_MODIFY(MCP3422_PGA_MASK, &config, adc->pga[req_channel]);
+
 		ret = mcp3422_update_config(adc, config);
 		if (ret < 0) {
 			mutex_unlock(&adc->lock);
 			return ret;
 		}
-		msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
+		msleep(mcp3422_read_times[FIELD_GET(MCP3422_SRATE_MASK, adc->config)]);
 	}
 
 	ret = mcp3422_read(adc, value, &config);
@@ -165,8 +158,8 @@ static int mcp3422_read_raw(struct iio_dev *iio,
 	struct mcp3422 *adc = iio_priv(iio);
 	int err;
 
-	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
-	u8 pga		 = MCP3422_PGA(adc->config);
+	u8 sample_rate = FIELD_GET(MCP3422_SRATE_MASK, adc->config);
+	u8 pga		 = FIELD_GET(MCP3422_PGA_MASK, adc->config);
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
@@ -182,7 +175,7 @@ static int mcp3422_read_raw(struct iio_dev *iio,
 		return IIO_VAL_INT_PLUS_NANO;
 
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
+		*val1 = mcp3422_sample_rates[FIELD_GET(MCP3422_SRATE_MASK, adc->config)];
 		return IIO_VAL_INT;
 
 	default:
@@ -200,7 +193,7 @@ static int mcp3422_write_raw(struct iio_dev *iio,
 	u8 temp;
 	u8 config = adc->config;
 	u8 req_channel = channel->channel;
-	u8 sample_rate = MCP3422_SAMPLE_RATE(config);
+	u8 sample_rate = FIELD_GET(MCP3422_SRATE_MASK, config);
 	u8 i;
 
 	switch (mask) {
@@ -212,10 +205,8 @@ static int mcp3422_write_raw(struct iio_dev *iio,
 			if (val2 == mcp3422_scales[sample_rate][i]) {
 				adc->pga[req_channel] = i;
 
-				config &= ~MCP3422_CHANNEL_MASK;
-				config |= MCP3422_CHANNEL_VALUE(req_channel);
-				config &= ~MCP3422_PGA_MASK;
-				config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
+				FIELD_MODIFY(MCP3422_CHANNEL_MASK, &config, req_channel);
+				FIELD_MODIFY(MCP3422_PGA_MASK, &config, adc->pga[req_channel]);
 
 				return mcp3422_update_config(adc, config);
 			}
@@ -242,10 +233,8 @@ static int mcp3422_write_raw(struct iio_dev *iio,
 			return -EINVAL;
 		}
 
-		config &= ~MCP3422_CHANNEL_MASK;
-		config |= MCP3422_CHANNEL_VALUE(req_channel);
-		config &= ~MCP3422_SRATE_MASK;
-		config |= MCP3422_SAMPLE_RATE_VALUE(temp);
+		FIELD_MODIFY(MCP3422_CHANNEL_MASK, &config, req_channel);
+		FIELD_MODIFY(MCP3422_SRATE_MASK, &config, temp);
 
 		return mcp3422_update_config(adc, config);
 
@@ -284,7 +273,7 @@ static ssize_t mcp3422_show_scales(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
-	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
+	u8 sample_rate = FIELD_GET(MCP3422_SRATE_MASK, adc->config);
 
 	return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
 		mcp3422_scales[sample_rate][0],
@@ -378,9 +367,9 @@ static int mcp3422_probe(struct i2c_client *client)
 
 	/* meaningful default configuration */
 	config = (MCP3422_CONT_SAMPLING
-		| MCP3422_CHANNEL_VALUE(0)
-		| MCP3422_PGA_VALUE(MCP3422_PGA_1)
-		| MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
+		| FIELD_PREP(MCP3422_CHANNEL_MASK, 0)
+		| FIELD_PREP(MCP3422_PGA_MASK, MCP3422_PGA_1)
+		| FIELD_PREP(MCP3422_SRATE_MASK, MCP3422_SRATE_240));
 	err = mcp3422_update_config(adc, config);
 	if (err < 0)
 		return err;
-- 
2.34.1

Re: [PATCH v2 2/2] iio: adc: mcp3422: write bit operations with bitfield macros

[Andy Shevchenko]

On Fri, Apr 17, 2026 at 01:57:47PM -0300, Marcelo Machado Lage wrote:
> Replace manual bit manipulations with FIELD_GET(), FIELD_PREP() and
> FIELD_MODIFY() calls. The resulting code is more readable and
> maintainable, and 6 macros previously defined in the header are not
> needed anymore.

> Following a request by Jonathan Cameron, this version of the patch
> has 3 less macros than v1, now replaced by inline calls of FIELD_GET().
> Thanks, Jonathan! 

This paragraph has to be in the comment block...

> Signed-off-by: Marcelo Machado Lage <marcelomlage@usp.br>
> Co-developed-by: Vinicius Lira <vinilira@usp.br>
> Signed-off-by: Vinicius Lira <vinilira@usp.br>
> ---

...id est somewhere here.

>  drivers/iio/adc/mcp3422.c | 51 +++++++++++++++------------------------
>  1 file changed, 20 insertions(+), 31 deletions(-)

...

> static int mcp3422_read_raw(struct iio_dev *iio,

>  	struct mcp3422 *adc = iio_priv(iio);
>  	int err;
>  
> -	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
> -	u8 pga		 = MCP3422_PGA(adc->config);
> +	u8 sample_rate = FIELD_GET(MCP3422_SRATE_MASK, adc->config);
> +	u8 pga		 = FIELD_GET(MCP3422_PGA_MASK, adc->config);

Please, use common practices and be aligned with the already used style in this
driver. These lines:
- has to be part of the definition block (no blank lines)
- use a single-space indentation approach (no need many spaces before =)
- be located in the form of longest line first (reversed xmas tree order)

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 1/2] iio: adc: mcp3422: rewrite mask macros using bitfield macros

[David Lechner]

On 4/17/26 11:57 AM, Marcelo Machado Lage wrote:
> Rewrite MCP3422_CHANNEL_MASK, MCP3422_PGA_MASK, MCP3422_PGA_MASK
> and MCP3422_CONT_SAMPLING using GENMASK() and BIT() macros from
> bitfield.h.
> 
> The other macros MCP3422_SRATE_{240, 60, 15, 3} were not changed
> because they are also used as array indices.
> 
> Signed-off-by: Marcelo Machado Lage <marcelomlage@usp.br>
> Co-developed-by: Vinicius Lira <vinilira@usp.br>
> Signed-off-by: Vinicius Lira <vinilira@usp.br>
> ---
>  drivers/iio/adc/mcp3422.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
> index 50834fdcf738..59bf73304588 100644
> --- a/drivers/iio/adc/mcp3422.c
> +++ b/drivers/iio/adc/mcp3422.c
> @@ -13,6 +13,7 @@
>   * voltage unit is nV.
>   */
>  
> +#include <linux/bits.h>
>  #include <linux/err.h>
>  #include <linux/i2c.h>
>  #include <linux/module.h>
> @@ -25,9 +26,9 @@
>  #include <linux/iio/sysfs.h>
>  
>  /* Masks */
> -#define MCP3422_CHANNEL_MASK	0x60
> -#define MCP3422_PGA_MASK	0x03
> -#define MCP3422_SRATE_MASK	0x0C
> +#define MCP3422_CHANNEL_MASK	GENMASK(6, 5)
> +#define MCP3422_PGA_MASK	GENMASK(1, 0)
> +#define MCP3422_SRATE_MASK	GENMASK(3, 2)

Would be nice to sort these in logical order (highest to lowest)
while we are touching this.

>  #define MCP3422_SRATE_240	0x0
>  #define MCP3422_SRATE_60	0x1
>  #define MCP3422_SRATE_15	0x2
> @@ -36,7 +37,7 @@
>  #define MCP3422_PGA_2	1
>  #define MCP3422_PGA_4	2
>  #define MCP3422_PGA_8	3
> -#define MCP3422_CONT_SAMPLING	0x10
> +#define MCP3422_CONT_SAMPLING	BIT(4)
>  
>  #define MCP3422_CHANNEL(config)	(((config) & MCP3422_CHANNEL_MASK) >> 5)
>  #define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)

Re: [PATCH v2 1/2] iio: adc: mcp3422: rewrite mask macros using bitfield macros

[Jonathan Cameron]

On Fri, 17 Apr 2026 13:57:46 -0300
Marcelo Machado Lage <marcelomlage@usp.br> wrote:

> Rewrite MCP3422_CHANNEL_MASK, MCP3422_PGA_MASK, MCP3422_PGA_MASK
> and MCP3422_CONT_SAMPLING using GENMASK() and BIT() macros from
> bitfield.h.
> 
> The other macros MCP3422_SRATE_{240, 60, 15, 3} were not changed
> because they are also used as array indices.
> 
> Signed-off-by: Marcelo Machado Lage <marcelomlage@usp.br>
> Co-developed-by: Vinicius Lira <vinilira@usp.br>
> Signed-off-by: Vinicius Lira <vinilira@usp.br>
> ---
>  drivers/iio/adc/mcp3422.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
> index 50834fdcf738..59bf73304588 100644
> --- a/drivers/iio/adc/mcp3422.c
> +++ b/drivers/iio/adc/mcp3422.c
> @@ -13,6 +13,7 @@
>   * voltage unit is nV.
>   */
>  
> +#include <linux/bits.h>
>  #include <linux/err.h>
>  #include <linux/i2c.h>
>  #include <linux/module.h>
> @@ -25,9 +26,9 @@
>  #include <linux/iio/sysfs.h>
>  
>  /* Masks */

This comment covers the first few defines, but not the reset.
Delete it whilst you are here to avoid future confusion.

> -#define MCP3422_CHANNEL_MASK	0x60
> -#define MCP3422_PGA_MASK	0x03
> -#define MCP3422_SRATE_MASK	0x0C
> +#define MCP3422_CHANNEL_MASK	GENMASK(6, 5)
> +#define MCP3422_PGA_MASK	GENMASK(1, 0)
> +#define MCP3422_SRATE_MASK	GENMASK(3, 2)
>  #define MCP3422_SRATE_240	0x0
>  #define MCP3422_SRATE_60	0x1
>  #define MCP3422_SRATE_15	0x2
> @@ -36,7 +37,7 @@
>  #define MCP3422_PGA_2	1
>  #define MCP3422_PGA_4	2
>  #define MCP3422_PGA_8	3
> -#define MCP3422_CONT_SAMPLING	0x10
> +#define MCP3422_CONT_SAMPLING	BIT(4)
>  
>  #define MCP3422_CHANNEL(config)	(((config) & MCP3422_CHANNEL_MASK) >> 5)
>  #define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)